ZyXEL NBG334SH1 Users Manual

Chapter 7 LAN

Figure 55 Any IP Example

The Any IP feature does not apply to a computer using either a dynamic IP address or a static IP address that is in the same subnet as the ZyXEL Device’s IP address.

"You must enable NAT to use the Any IP feature on the ZyXEL Device.

Address Resolution Protocol (ARP) is a protocol for mapping an Internet Protocol address (IP address) to a physical machine address, also known as a Media Access Control or MAC address, on the local area network. IP routing table is defined on IP Ethernet devices (the ZyXEL Device) to decide which hop to use, to help forward data along to its specified destination.

The following lists out the steps taken, when a computer tries to access the Internet for the first time through the ZyXEL Device.

1When a computer (which is in a different subnet) first attempts to access the Internet, it sends packets to its default gateway (which is not the ZyXEL Device) by looking at the MAC address in its ARP table.

2When the computer cannot locate the default gateway, an ARP request is broadcast on the LAN.

3The ZyXEL Device receives the ARP request and replies to the computer with its own MAC address.

4The computer updates the MAC address for the default gateway to the ARP table. Once the ARP table is updated, the computer is able to access the Internet through the ZyXEL Device.

5When the ZyXEL Device receives packets from the computer, it creates an entry in the IP routing table so it can properly forward packets intended for the computer.

After all the routing information is updated, the computer can access the ZyXEL Device and the Internet as if it is in the same subnet as the ZyXEL Device.

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7.3 LAN IP Screen

Use this screen to change your basic LAN settings. Click Network > LAN.

Figure 56 LAN IP

The following table describes the labels in this screen.

Table 36 LAN IP

LABEL	DESCRIPTION
LAN TCP/IP
IP Address	Type the IP address of your ZyXEL Device in dotted decimal notation
	192.168.1.1 (factory default).
IP Subnet Mask	The subnet mask specifies the network number portion of an IP address. Your
	ZyXEL Device will automatically calculate the subnet mask based on the IP
	address that you assign. Unless you are implementing subnetting, use the
	subnet mask computed by the ZyXEL Device.
Apply	Click Apply to save your changes back to the ZyXEL Device.
Reset	Click Reset to begin configuring this screen afresh.

7.4 LAN IP Alias

IP alias allows you to partition a physical network into different logical networks over the same Ethernet interface. The ZyXEL Device supports three logical LAN interfaces via its single physical Ethernet interface with the ZyXEL Device itself as the gateway for each LAN network.

To change your ZyXEL Device’s IP alias settings, click Network > LAN > IP Alias. The screen appears as shown.

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Figure 57 LAN IP Alias

The following table describes the labels in this screen.

Table 37 LAN IP Alias

LABEL	DESCRIPTION
IP Alias 1,2	Select the check box to configure another LAN network for the ZyXEL Device.
IP Address	Enter the IP address of your ZyXEL Device in dotted decimal notation.
IP Subnet Mask	Your ZyXEL Device will automatically calculate the subnet mask based on the IP
	address that you assign. Unless you are implementing subnetting, use the
	subnet mask computed by the ZyXEL Device.
Apply	Click Apply to save your changes back to the ZyXEL Device.
Reset	Click Reset to begin configuring this screen afresh.

7.5 Advanced LAN Screen

To change your ZyXEL Device’s advanced IP settings, click Network > LAN > Advanced. The screen appears as shown.

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Figure 58 Advanced LAN

The following table describes the labels in this screen.

Table 38 Advanced LAN

LABEL	DESCRIPTION
Multicast	Select IGMP V-1 or IGMP V-2 or None. IGMP (Internet Group Multicast
	Protocol) is a network-layer protocol used to establish membership in a
	Multicast group - it is not used to carry user data. IGMP version 2 (RFC 2236)
	is an improvement over version 1 (RFC 1112) but IGMP version 1 is still in
	wide use. If you would like to read more detailed information about
	interoperability between IGMP version 2 and version 1, please see sections 4
	and 5 of RFC 2236.
Active	Select this if you want to let computers on different subnets use the ZyXEL
	Device.

Windows Networking (NetBIOS over TCP/IP): NetBIOS (Network Basic Input/Output System) are TCP or UDP broadcast packets that enable a computer to connect to and communicate with a LAN. For some dial-up services such as PPPoE or PPTP, NetBIOS packets cause unwanted calls. However it may sometimes be necessary to allow NetBIOS packets to pass through to the WAN in order to find a computer on the WAN.

Allow between LAN	Select this check box to forward NetBIOS packets from the LAN to the WAN
and WAN	and from the WAN to the LAN. If your firewall is enabled with the default policy
	set to block WAN to LAN traffic, you also need to enable the default WAN to
	LAN firewall rule that forwards NetBIOS traffic.
	Clear this check box to block all NetBIOS packets going from the LAN to the
	WAN and from the WAN to the LAN.
Apply	Click Apply to save your changes back to the ZyXEL Device.
Reset	Click Reset to begin configuring this screen afresh.

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8

DHCP Server

8.1 DHCP

DHCP (Dynamic Host Configuration Protocol, RFC 2131 and RFC 2132) allows individual clients to obtain TCP/IP configuration at start-up from a server. You can configure the ZyXEL Device as a DHCP server or disable it. When configured as a server, the ZyXEL Device provides the TCP/IP configuration for the clients. If DHCP service is disabled, you must have another DHCP server on your LAN, or else the computer must be manually configured.

8.2 DHCP Server General Screen

Click Network > DHCP Server. The following screen displays.

Figure 59 DHCP Server General

The following table describes the labels in this screen.

Table 39 DHCP Server General

LABEL	DESCRIPTION
Enable DHCP Server	DHCP (Dynamic Host Configuration Protocol, RFC 2131 and RFC 2132)
	allows individual clients (computers) to obtain TCP/IP configuration at startup
	from a server. Leave the Enable DHCP Server check box selected unless
	your ISP instructs you to do otherwise. Clear it to disable the ZyXEL Device
	acting as a DHCP server. When configured as a server, the ZyXEL Device
	provides TCP/IP configuration for the clients. If not, DHCP service is disabled
	and you must have another DHCP server on your LAN, or else the computers
	must be manually configured. When set as a server, fill in the following four
	fields.
IP Pool Starting	This field specifies the first of the contiguous addresses in the IP address
Address	pool.
Pool Size	This field specifies the size, or count of the IP address pool.
Apply	Click Apply to save your changes back to the ZyXEL Device.
Reset	Click Reset to begin configuring this screen afresh.

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8.3 DHCP Server Advanced Screen

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This screen allows you to assign IP addresses on the LAN to specific individual computers based on their MAC addresses. You can also use this screen to configure the DNS server information that the ZyXEL Device sends to the DHCP clients.

Every Ethernet device has a unique MAC (Media Access Control) address. The MAC address is assigned at the factory and consists of six pairs of hexadecimal characters, for example, 00:A0:C5:00:00:02.

To change your ZyXEL Device’s static DHCP settings, click Network > DHCP Server > Advanced. The following screen displays.

Figure 60 DHCP Server Advanced

The following table describes the labels in this screen.

Table 40 DHCP Server Advanced

LABEL	DESCRIPTION
#	This is the index number of the static IP table entry (row).
MAC Address	Type the MAC address (with colons) of a computer on your LAN.
IP Address	Type the LAN IP address of a computer on your LAN.

DNS Servers Assigned by DHCP Server

The ZyXEL Device passes a DNS (Domain Name System) server IP address (in the order you specify here) to the DHCP clients. The ZyXEL Device only passes this information to the LAN DHCP clients when you select the Enable DHCP Server check box. When you clear the Enable DHCP Server check box, DHCP service is disabled and you must have another DHCP sever on your LAN, or else the computers must have their DNS server addresses manually configured.

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	Table 40 DHCP Server Advanced
	LABEL	DESCRIPTION
	First DNS Server	Select From ISP if your ISP dynamically assigns DNS server information (and
	Second DNS	the ZyXEL Device's WAN IP address). The field to the right displays the (read-
	Server	only) DNS server IP address that the ISP assigns.
	Third DNS Server	Select User-Defined if you have the IP address of a DNS server. Enter the DNS
		server's IP address in the field to the right. If you chose User-Defined, but leave
		the IP address set to 0.0.0.0, User-Defined changes to None after you click
		Apply. If you set a second choice to User-Defined, and enter the same IP
		address, the second User-Defined changes to None after you click Apply.
		Select DNS Relay to have the ZyXEL Device act as a DNS proxy. The ZyXEL
		Device's LAN IP address displays in the field to the right (read-only). The ZyXEL
		Device tells the DHCP clients on the LAN that the ZyXEL Device itself is the
		DNS server. When a computer on the LAN sends a DNS query to the ZyXEL
		Device, the ZyXEL Device forwards the query to the ZyXEL Device's system
		DNS server (configured in the WAN > Internet Connection screen) and relays
		the response back to the computer. You can only select DNS Relay for one of
		the three servers; if you select DNS Relay for a second or third DNS server, that
		choice changes to None after you click Apply.
		Select None if you do not want to configure DNS servers. If you do not configure
		a DNS server, you must know the IP address of a computer in order to access it.
	Apply	Click Apply to save your changes back to the ZyXEL Device.
	Reset	Click Reset to begin configuring this screen afresh.

8.4 Client List Screen

The DHCP table shows current DHCP client information (including IP Address, Host Name and MAC Address) of all network clients using the ZyXEL Device’s DHCP server.

Configure this screen to always assign an IP address to a MAC address (and host name). Click

Network > DHCP Server > Client List.

"You can also view a read-only client list by clicking the DHCP Table (Details...) hyperlink in the Status screen.

The following screen displays.

Figure 61 Client List

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The following table describes the labels in this screen.

Table 41 Client List

LABEL	DESCRIPTION
#	This is the index number of the host computer.
IP Address	This field displays the IP address relative to the # field listed above.
Host Name	This field displays the computer host name.
MAC Address	The MAC (Media Access Control) or Ethernet address on a LAN (Local Area
	Network) is unique to your computer (six pairs of hexadecimal notation).
	A network interface card such as an Ethernet adapter has a hardwired
	address that is assigned at the factory. This address follows an industry
	standard that ensures no other adapter has a similar address.
Reserve	Select this check box to have the ZyXEL Device always assign this IP address
	to this MAC address (and host name). After you click Apply, the MAC
	address and IP address also display in the Advanced screen (where you can
	edit them).
Refresh	Click Refresh to reload the DHCP table.

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9

Network Address Translation

(NAT)

This chapter discusses how to configure NAT on the ZyXEL Device.

9.1 NAT Overview

NAT (Network Address Translation - NAT, RFC 1631) is the translation of the IP address of a host in a packet. For example, the source address of an outgoing packet, used within one network is changed to a different IP address known within another network.

9.2Using NAT

"You must create a firewall rule in addition to setting up NAT, to allow traffic from the WAN to be forwarded through the ZyXEL Device.

9.2.1 Port Forwarding: Services and Port Numbers

A port forwarding set is a list of inside (behind NAT on the LAN) servers, for example, web or FTP, that you can make accessible to the outside world even though NAT makes your whole inside network appear as a single machine to the outside world.

Use the Application screen to forward incoming service requests to the server(s) on your local network. You may enter a single port number or a range of port numbers to be forwarded, and the local IP address of the desired server. The port number identifies a service; for example, web service is on port 80 and FTP on port 21. In some cases, such as for unknown services or where one server can support more than one service (for example both FTP and web service), it might be better to specify a range of port numbers.

In addition to the servers for specified services, NAT supports a default server. A service request that does not have a server explicitly designated for it is forwarded to the default server. If the default is not defined, the service request is simply discarded.

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"Many residential broadband ISP accounts do not allow you to run any server processes (such as a Web or FTP server) from your location. Your ISP may periodically check for servers and may suspend your account if it discovers any active services at your location. If you are unsure, refer to your ISP.

9.2.2Configuring Servers Behind Port Forwarding Example

Let's say you want to assign ports 21-25 to one FTP, Telnet and SMTP server (A in the example), port 80 to another (B in the example) and assign a default server IP address of 192.168.1.35 to a third (C in the example). You assign the LAN IP addresses and the ISP assigns the WAN IP address. The NAT network appears as a single host on the Internet

Figure 62 Multiple Servers Behind NAT Example

9.3 General NAT Screen

Click Network > NAT to open the General screen.

Figure 63 NAT General

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The following table describes the labels in this screen.

Table 42 NAT General

LABEL	DESCRIPTION
Network Address	Network Address Translation (NAT) allows the translation of an Internet protocol
Translation	address used within one network (for example a private IP address used in a local
	network) to a different IP address known within another network (for example a
	public IP address used on the Internet).
	Select the check box to enable NAT.
Default Server	In addition to the servers for specified services, NAT supports a default server. A
	default server receives packets from ports that are not specified in the Application
	screen.
	If you do not assign a Default Server IP address, the ZyXEL Device discards all
	packets received for ports that are not specified in the Application screen or
	remote management.
Apply	Click Apply to save your changes back to the ZyXEL Device.
Reset	Click Reset to begin configuring this screen afresh.

9.4 NAT Application Screen

Port forwarding allows you to define the local servers to which the incoming services will be forwarded. To change your ZyXEL Device’s port forwarding settings, click Network > NAT

> Application. The screen appears as shown.

"If you do not assign a Default Server IP address in the NAT > General screen, the ZyXEL Device discards all packets received for ports that are not specified in this screen or remote management.

Refer to Appendix I on page 257 for port numbers commonly used for particular services.

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Figure 64 NAT Application

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The following table describes the labels in this screen.

Table 43 NAT Application

LABEL	DESCRIPTION
Game List Update	A game list includes the pre-defined service name(s) and port number(s). You can
	edit and upload it to the ZyXEL Device to replace the existing entries in the second
	field next to Service Name.
File Path	Type in the location of the file you want to upload in this field or click Browse... to
	find it.
Browse...	Click Browse... to find the.txt file you want to upload. Remember that you must
	decompress compressed (.zip) files before you can upload them.
Update	Click Update to begin the upload process. This process may take up to two
	minutes.
Add Application
Rule
Active	Select the check box to enable this rule and the requested service can be
	forwarded to the host with a specified internal IP address.
	Clear the checkbox to disallow forwarding of these ports to an inside server
	without having to delete the entry.
Service Name	Type a name (of up to 31 printable characters) to identify this rule in the first field
	next to Service Name. Otherwise, select a predefined service in the second field
	next to Service Name. The predefined service name and port number(s) will
	display in the Service Name and Port fields.

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	Table 43 NAT Application (continued)
	LABEL	DESCRIPTION
	Port	Type a port number(s) to be forwarded.
		To specify a range of ports, enter a hyphen (-) between the first port and the last
		port, such as 10-20.
		To specify two or more non-consecutive port numbers, separate them by a comma
		without spaces, such as 123,567.
	Server IP Address	Type the inside IP address of the server that receives packets from the port(s)
		specified in the Port field.
	Apply	Click Apply to save your changes to the Application Rules Summary table.
	Reset	Click Reset to not save and return your new changes in the Service Name and
		Port fields to the previous one.
	Application Rules
	Summary
	#	This is the number of an individual port forwarding server entry.
	Active	This icon is turned on when the rule is enabled.
	Name	This field displays a name to identify this rule.
	Port	This field displays the port number(s).
	Server IP Address	This field displays the inside IP address of the server.
	Modify	Click the Edit icon to display and modify an existing rule setting in the fields under
		Add Application Rule.
		Click the Remove icon to delete a rule.

9.4.1 Game List Example

Here is an example game list text file. The index number, service name and associated port(s) are specified by semi-colons (no spaces). Use the name=xxx (where xxx is the service name) to create a new service. Port range can be separated with a hyphen (-) (no spaces). Multiple (non-consecutive) ports can be separated by commas.

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Figure 65 Game List Example

version=1

1;name=Battlefield 1942;port=14567,22000,23000-23009,27900,28900 2;name=Call of Duty;port=28960

3;name=Civilization IV;port=2056 4;name=Diablo I and II;port=6112-6119,4000 5;name=Doom 3;port=27666 6;name=F.E.A.R;port=27888

7;name=Final Fantasy XI;port=25,80,110,443,50000-65535 8;name=Guild Wars;port=6112,80

9;name=Half Life;port=6003,7002,27005,27010,27011,27015 10;name=Jedi Knight III: Jedi Academy;port=28060-28062,28070-28081 11;name=Need for Speed: Hot Pursuit 2;port=1230,8511- 8512,27900,28900,61200-61230

12;name=Neverwinter Nights;port=5120-5300,6500,27900,28900 13;name=Quake 2;port=27910

14;name=Quake 3;port=27660,27960

15;name=Rainbow Six 3: Raven Shield;port=7777-7787,8777-8787 16;name=Serious Sam II;port=25600-25605

17;name=Silent Hunter III;port=17997-18003 18;name=Soldier of Fortune II;port=20100-20112 19;name=Starcraft;port=6112-6119,4000 20;name=Star Trek: Elite Force II;port=29250,29256 21;name=SWAT 4;port=10480-10483

22;name=Warcraft II and III;port=6112-6119,4000 23;name=World of Warcraft;port=3724

9.5 Trigger Port Forwarding

Some services use a dedicated range of ports on the client side and a dedicated range of ports on the server side. With regular port forwarding you set a forwarding port in NAT to forward a service (coming in from the server on the WAN) to the IP address of a computer on the client side (LAN). The problem is that port forwarding only forwards a service to a single LAN IP address. In order to use the same service on a different LAN computer, you have to manually replace the LAN computer's IP address in the forwarding port with another LAN computer's IP address.

Trigger port forwarding solves this problem by allowing computers on the LAN to dynamically take turns using the service. The ZyXEL Device records the IP address of a LAN computer that sends traffic to the WAN to request a service with a specific port number and protocol (a "trigger" port). When the ZyXEL Device's WAN port receives a response with a specific port number and protocol ("incoming" port), the ZyXEL Device forwards the traffic to the LAN IP address of the computer that sent the request. After that computer’s connection for that service closes, another computer on the LAN can use the service in the same manner. This way you do not need to configure a new IP address each time you want a different LAN computer to use the application.

9.5.1 Trigger Port Forwarding Example

The following is an example of trigger port forwarding.

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Figure 66 Trigger Port Forwarding Process: Example

1Jane requests a file from the Real Audio server (port 7070).

2Port 7070 is a “trigger” port and causes the ZyXEL Device to record Jane’s computer IP address. The ZyXEL Device associates Jane's computer IP address with the "incoming" port range of 6970-7170.

3The Real Audio server responds using a port number ranging between 6970-7170.

4The ZyXEL Device forwards the traffic to Jane’s computer IP address.

5Only Jane can connect to the Real Audio server until the connection is closed or times out. The ZyXEL Device times out in three minutes with UDP (User Datagram Protocol), or two hours with TCP/IP (Transfer Control Protocol/Internet Protocol).

9.5.2Two Points To Remember About Trigger Ports

1Trigger events only happen on data that is going coming from inside the ZyXEL Device and going to the outside.

2If an application needs a continuous data stream, that port (range) will be tied up so that another computer on the LAN can’t trigger it.

9.6 NAT Advanced Screen

To change your ZyXEL Device’s trigger port settings, click Network > NAT > Advanced. The screen appears as shown.

"Only one LAN computer can use a trigger port (range) at a time.

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Figure 67 NAT Advanced

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The following table describes the labels in this screen.

Table 44 NAT Advanced

LABEL	DESCRIPTION
Max NAT/Firewall	Type a number ranging from 1 to 2048 to limit the number of NAT/firewall sessions
Session Per User	that a host can create.
	When computers use peer to peer applications, such as file sharing
	applications, they may use a large number of NAT sessions. If you do not
	limit the number of NAT sessions a single client can establish, this can result in all
	of the available NAT sessions being used. In this case, no additional NAT
	sessions can be established, and users may not be able to access the Internet.
	Each NAT session establishes a corresponding firewall session. Use this field to
	limit the number of NAT/firewall sessions each client computer can establish
	through the ZyXEL Device.
	If your network has a small number of clients using peer to peer applications, you
	can raise this number to ensure that their performance is not degraded by the
	number of NAT sessions they can establish. If your network has a large number of
	users using peer to peer applications, you can lower this number to ensure no
	single client is using all of the available NAT sessions.
#	This is the rule index number (read-only).
Name	Type a unique name (up to 15 characters) for identification purposes. All
	characters are permitted - including spaces.
Incoming	Incoming is a port (or a range of ports) that a server on the WAN uses when it
	sends out a particular service. The ZyXEL Device forwards the traffic with this port
	(or range of ports) to the client computer on the LAN that requested the service.
Start Port	Type a port number or the starting port number in a range of port numbers.
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	LABEL	DESCRIPTION
	End Port	Type a port number or the ending port number in a range of port numbers.
	Trigger	The trigger port is a port (or a range of ports) that causes (or triggers) the ZyXEL
		Device to record the IP address of the LAN computer that sent the traffic to a
		server on the WAN.
	Start Port	Type a port number or the starting port number in a range of port numbers.
	End Port	Type a port number or the ending port number in a range of port numbers.
	Apply	Click Apply to save your changes back to the ZyXEL Device.
	Reset	Click Reset to begin configuring this screen afresh.

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